=80-6+800-5+8000-4+80000-3+800000-2+8000000- 1

=9999990-2 1=9999969

2.(-5 5/6)+(-9 2/30+ 17 3/4+(-3 1/2)

=- 14 and 27/30+ 14 and1/4 =1/4-27/30 = (30-108)/120 =

3. (-May 6, 2000)+(-1999 2/3)+4000 3/4+(-1and 1/2)

=-3999 and 1/6+3999 and 1/4.

= 1/4- 1/6= 1/ 12

4.(-4 1/2)-{3 2/5-[(-0. 13)-(-0.33)]}

=(-4 1/2)-{3 2/5-0.2}

=(-4 1/2)-{3 2/5- 1/5}

=(-4 and 1/2)-3 and 1/5.

=-7 7/ 10=-7.7

5. 1/2+ 1/6+ 1/ 12+ 1/20+ 1/30+ 1/42+ 1/56

=( 1/6+ 1/ 12)+ 1/20+ 1/30+ 1/42+( 1/2+ 1/56)

=3/ 12+ 1/20+ 1/30+ 1/42+29/56

= 1/4+ 1/20+ 1/30+ 1/42+29/56

=6/20+(42+30)/ 1260+29/56

=3/ 10+72/ 1260+29/56

=3/ 10+2/35+29/56

=(42+8)/ 140+29/56

=50/ 140+29/56

=5/ 14+29/56

=(20+29)/56

=49/56